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– – – Letture – – –


Joseph Priestley, Experiments and observations on different kinds of air, London, 1775

One reason for the present publication has been the favourable reception of those of my Observations on different kinds of air, which were published in the Philosophical Transactions for the year 1772. [...]
As to myself, I find it absolutely impossible to produce a work on this subject that shall be any thing like complete. My first publication I acknowledged to be very imperfect, and the present, I am as ready to acknowledge, is still more so.
But paradoxical as it may seem, this will ever be the case in the progress of natural science, so long as the works of God are, like himself, infinite and inexhaustible. In completing one discovery we never fail to get an imperfect knowledge of others, of which we could have no idea before; so that we cannot solve one doubt without creating several new ones.
Travelling on this ground resembles Pope’s description of travelling among the Alps, with this difference, that here there is not only a succession, but an increase of new objects and new difficulties.

So pleas’d at the first the tow’ring Alps we try,
Mount o’er the vales, and seem to tread the sky.
Th’ eternal snows appear already past,
And the first clouds and the mountains seem the last,
But those attain’d, we tremble to survey
The growing labours of the lengthen’d way.
Th’ increasing prospect tires our wand’ring eyes,
Hills peep o’er hills, and Alps on Alps arise..